h1::before {
	content: "第五周作业"
}
p,a {
	color: green;
}
div p, div p a {
	color: red;
}

h2 {
	color: brown;
}
h2 {
	color: orange;
}
#length {
	font-size: 2em
	color:#ccc;
	color: rgba(100, 100, 90, 0.8);
	font-family: "黑体"
	font-style:italic;
	font-weight: bolder;

}